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Copyright of Science & Technology of Food Industry is the property of Science & Technology of Food Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to investigate the potential mechanism of melatonin (MT) to alleviate the browning of postharvest lotus seeds. 1) The samples were treated with the distilled water, nitric oxide (NO), MT, the inhibitor of nitric oxide synthase (NOS) nomega-nitro-L-arginine methyl ester (L-NAME), the inhibitor of nitrate reductase (NR) tungstate (TUN), and the scavenger of NO carboxy-PTIO (cPTIO), MT + L-NAME, MT + TUN and MT + cPTIO. A systematic analysis was implemented to explore the possible pathway of NO biosynthesis in the lotus seeds. Then, the levels of key enzymes and substances were determined to involve in the NO biosynthesis. The results showed that the endogenous NO content of the MT treated lotus seeds was significantly higher than that of the control. The NOS activity of lotus seeds treated with MT was promoted by 60.36%−71.08% before 3 days of storage. In addition, the MT treatment significantly increased the contents of Larginine and citrulline (P <0.05), which were the key substances in the NO biosynthesis. It was notable that the citrulline content in the MT treated sample was 1.44~1.59 times than those of the controls. By contrast, there was the varying influence of MT treatment on the activity of NR in lotus seeds. There was the beneficial effect of MT on the lotus seeds and the endogenous NO content of the tissue, when the MT was combined with the inhibitor of NR (TUN). However, this beneficial effect disappeared, when the MT was combined with the inhibitor of NOS (L-NAME) for treating the lotus seeds. The endogenous NO content in this treatment was significantly lower than that in the control. Therefore, the exogenous MT treatment was induced the NO biosynthesis in lotus seeds through the pathway of NOS. 2) The potential mechanism of MT was clarified to regulate the browning of lotus seeds. The phenolic compounds were identified in the lotus seeds using a LC20 HPLC (Shimadzu, Japan) system coupled to a TripleTOF® 5600 + quadrupole time-of-flight (QTOF) mass spectrometer equipped with a DuoSpray™ ion source (Sciex, Ontario, Canada). It was found that there were six flavanols and seven phenolic acids in the lotus seeds, and the content of catechin, a type of flavanol, accounts for over 60% of the total phenol content, the following was ellagitannin, a type of phenolic acid, accounts for 7.45% of the total phenol content. It infers that the catechin was the major phenolic compound of lotus seeds. The flavan-3-ol was the most common direct natural substrate of polyphenol oxidase (PPO) in the plant, especially for the catechin and epicatechin. Thereby, the potential mechanism of MT was determined, where the catechin metabolism was regulated to induce the NO production in the following experiments. The results indicated that the activity of PPO in the MT treated lotus seeds was lower by 35.39%−57.36% than those in the control. What’s more, the MT treatment significantly increased the activities of key enzymes, including cinnamate-4-hydroxylase, dihydroflavonol reductase, chalcone synthase, chalcone isomerase and colorless anthocyanin reductase (P <0.05) in the catechin synthetic metabolism. As a result, the content of catechin in the MT treated sample was higher by 15.35%−47.86% than those in the control after 1 days of storage. Whereas, this positive effect was negated, when the MT was combined with LNAME or cPTIO for treating lotus seeds. Therefore, it was concluded that the exogenous MT treatment was induced the biosynthesis of NO through NOS pathway, and then the accumulated NO acted on the catechin metabolism of lotus seeds. The MT treatment was used to inhibit the PPO activity, and then the catechin was suppressed to participate in the enzymatic browning; The biosynthesis of catechin was promoted in this treatment. Consequently, the lotus seeds browning was also alleviated by the MT treatment. These findings can provide the theoretical and technical support to preservation of lotus seeds and the signal transduction between MT and NO. [ABSTRACT FROM AUTHOR]

Ber fruit (Zizyphus mauritiana Lamk) contains abundant polyphenols and is highly susceptible to enzymatic browning after harvest. In order to reduce browning and maintain fruit quality of ber fruit, a factorial experiment was conducted in a completely randomized design with four replications. Experimental treatments included control, Zataria multiflora essential oil (ZEO) (0.5%), ZEO (1%), Aloe vera gel -based (20%) enriched with sesame oil 1%, honey 1% (ASH), ASH + ZEO (0.5%), ASH + ZEO (1%) and storage time (0, 7, 14, 21 and 28 days) at 6 ± 1°C and relative humidity of 90±5%. The results showed that edible coating application had significant effect on the quality characteristics of the ber fruit during storage. The combination of ASH with ZEO (0.5%), as an edible coating, significantly alleviated enzymatic browning by reducing PPO and POD activities on fruit during 28 days of storage. Fruits treated with ASH with ZEO (0.5%) reduced browning index (70%) compared to the control; while increased total phenol content and antioxidant activity (18.14%, and 31.16%, respectively) compared to the control after 28 days of storage. Also, ASH in combination with ZEO (0.5%) treatment decreased electrolyte leakage and malondialdehyde (19.7%, and 17.8%, respectively) compared to the control after 28 days of storage. These results indicated that ASH edible coating in combination with ZEO (0.5%) can be a useful method for delaying ripening and senescence, extending the storage life of ber fruit. [ABSTRACT FROM AUTHOR]

From a quality standpoint, it is desirable to preserve the characteristics of fresh-cut potatoes at their peak. However, due to the mechanical tissue damage during the cutting process, potatoes are susceptible to enzymatic browning. This study pertains to the selection of the appropriate osmotic dehydration (OD), high pressure (HP), and pulsed electric fields (PEF) processing conditions leading to effective quality retention of potato cuts. PEF (0.5 kV/cm, 200 pulses) or HP (400 MPa, 1 min) treatments prior to OD (35 °C, 120 min) were found to promote the retention of the overall quality (texture and color) of the samples. The incorporation of anti-browning agents (ascorbic acid and papain) into the osmotic solution improved the color retention, especially when combined with PEF or HP due to increased solid uptake (during OD) as indicated by DEI index (2.30, 1.93, and 2.10 for OD treated 120 min, non-pre-treated, HP pre-treated, and PEF pre-treated samples, respectively). PEF and HP combined with OD and anti-browning agent enrichment are sought to improve the quality and microbial stability of fresh-cut potatoes during refrigerator storage. Untreated fresh-cut potatoes were characterized by color degradation from the 2nd day of storage at 4 °C, and presented microbial growth (total viable counts: 6 log (CFU)/g) at day 6, whereas pre-treated potato samples retained their color and microbiologically stability after 6 days of cold storage (total viable counts, <4 log(CFU)/g). [ABSTRACT FROM AUTHOR]

Minimally processed apples (MPA) are tasty, easy to consume, nutritious (sugars, vitamins and minerals) and functional (dietary fiber and secondary metabolites such as flavonoids, isoflavonoids, carotenoids and phenolic acids). However, following processing, pulp browning rapidly compromises its natural color, texture, flavor, and health benefits. To deal with this problem, refrigerated storage combined with antioxidant treatment is usually employed. In this study, kojic acid (KA), a metabolite of fungi (Aspergillus and Penicillium) widely used as a food additive to prevent enzymatic browning and bacterial growth, was used as an antioxidant. It was tested at three different concentrations (0.03%, 0.05% and 0.07%) in minimally processed 'Royal Gala' apples, for up to 9 days of cold storage. Distilled water and 0.6% L-cysteine chloride were used as negative and positive controls, respectively. Browning index, Hue angle, antioxidant activity, total phenolic compounds, enzyme activity (peroxidase and polyphenoloxidase) and sensory attributes were evaluated. The browning of 'Royal Gala' apples was dependent on KA concentration for all related variables (L*, a* e b*, Hue angle and browning index). KA at concentrations of 0.05% and 0.07% showed results similar to the positive control (L-cysteine). The values of total phenolic compounds and antioxidant activity were stable for apples treated with KA 0.07% during the 9 days of storage. The peroxidase activity of apples treated with KA 0.07% was similar to that of apples treated with L-cysteine 0.6%. Sensorial analysis showed that KA-treated apples scored better than L-cysteine-treated apples. KA 0.07% was effective in controlling the browning of 'Royal Gala' apple pulp, without altering the sensory characteristics during the 9 days of refrigerated storage. [ABSTRACT FROM AUTHOR]

Sulfur dioxide is the most used additive today for preventing browning in grape musts and wines. However, since wine consumers are increasingly interested in healthier wines, the wine industry is keen to reduce its use. Some promising alternatives to sulfur dioxide have been proposed in recent years, including glutathione, both pure and in the form of inactivated yeasts, and Metschnikowia pulcherrima used as a bioprotective agent. Some information exists about the protective effect against oxidation of glutathione but there is very few about the use of bioprotection for that purpose. Supplementation with glutathione, regardless of the commercial form, reduced oxygen consumption and browning intensity when laccase was not present in the grape juice. Metschnikowia pulcherrima also reduced browning intensity in the absence of laccase but increased the total oxygen consumption. However, in the presence of laccase, glutathione and Metschnikowia pulcherrima were not effective enough to adequately prevent the grape juice from browning. Glutathione, both pure and in the form of inactivated yeasts, and Metschnikowia pulcherrima are interesting tools for protecting grape must against browning, and thus reducing the use of sulfur dioxide. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology / Zhongguo Shipin Xuebao is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Enzymatic browning is a common limiting factor in the fruit industry because it causes significant losses through fresh product deterioration, affecting taste, flavor, and nutrition. Artocarpus odoratissimus, locally known as terap, is an exotic indigenous fruit to Borneo. This fruit remains underutilized due to its perishability, short shelf-life, and peel browning. Currently, no information has apparently been published on the browning mechanisms of A. odoratissimus. Thus, the present study aims to evaluate the degree of browning and enzymatic activities in relation to the phytochemical contents in A. odoratissimus during postharvest ripening. The experimental design consists of packaging (without packaging and with packaging) and storage temperatures (ambient at 25 °C, and cold storage at 10 °C), which were arranged in a randomized complete block design. Findings showed significantly higher weight loss in fruit stored at 25 °C on days 4 (T1) at 12.20 ± 0.19% and 8 (T5) at 11.09 ± 0.24%. The degree of browning was higher in the fruits stored with packaging at 25 °C, collected on day 4 at 0.48 ± 0.01 and day 8 at 0.51 ± 0.02, and consequently, the phenylalanine ammonia-lyase (671.00 ± 5.25 UE g−1 min−1) and polyphenol oxidase (670.00 ± 2.56 UE g−1 min−1) enzymatic activities were also higher. The lower enzymatic activities were recorded in the fruit stored at 10 °C without packaging, resulting in the least degree of browning. The fruit with the lowest enzymatic activities was stored at 10 °C without packaging, resulting in the least amount of browning. This trend is supported by lower total phenolic content (TPC) and is explained by a strong positive correlation between TPC and PAL (r = 0.927). Low-temperature storage was effective in reducing the effect of browning and deterioration on A. odoratissimus for up to 16 days. The results not only provided insights into the peel browning in A. odoratissimus but also guidance on controlling postharvest fruit browning. [ABSTRACT FROM AUTHOR]

Diode laser irradiation is a novel approach applied to preserve the quality of fresh commodities and minimise oxidative processes, including browning in fresh-cut products. The objective of this study was to investigate the efficacy of diode laser treatment in enhancing the quality of celtuce slices during refrigerated storage at 4 °C. The celtuce slices were subjected to a 660 or 450 nm diode laser for 5 min and then stored for 10 d. Both laser treatments hindered the progression of weight loss and firmness increase in the celtuce slices. The use of a 450 nm diode laser effectively prevented the development of browning and preserved the surface colour by inhibiting the increase in a * and overall colour difference values, as compared to other treatments, during storage for 10 d. The diode laser treatment suppressed the increase in oxidative stress by lowering the levels of MDA, H 2 O 2 , and O- 2 while retaining a high level of DPPH scavenging activity, AsA, and antioxdant enzyme activities, including SOD, CAT, APX, and GR, in comparison to the untreated slices. The treatment enhanced chlorophylls content due to the up-regulation of LsHEMA1 gene and down-regulation of LsNYC1 gene. The treatment also inhibited factors involving enzymatic browning reaction by suppressing PAL activity, total phenols content, PPO activity and LsPPO gene expression. These suggest that the blue diode laser exposure at 450 nm for 5 min is an effective approach hindering oxidative stress and discoloration of celtuce slices during storage. [Display omitted] • Diode laser exposured at 450 nm for 5 min could maintain the quality of celtuce slices. • The treatment preserved the green colour and inhibited the browning of the slices. • The treatment improved antioxidants and inhibited oxidative responses of the slices. [ABSTRACT FROM AUTHOR]

Enzymatic browning is an important issue impacting the shelf life of fresh-cut potatoes. Using browning inhibitors is an effective method to solve the issue. This research aimed to identify novel and safe inhibitors of enzymatic browning. The research first investigated the inhibitory role of furan compounds in enzymatic browning, then explored the anti-browning effect of furaneol and the involved mechanism. Among the eight tested furan compounds classified as flavorings in food additives, seven showed anti-browning effects, of which three demonstrated superior efficacy in delaying browning compared to the others. Based on the efficacy and odor, furaneol as one natural flavor composition of fresh fruit was selected to be further investigated. At 4 °C, control potatoes browned on day 1. However, furaneol at concentrations of 4 and 8 mM prevented the fresh-cut potatoes from browning for up to 10 d, and their anti-browning efficacies reached that of sodium bisulfite. Sensory evaluation showed the treated fresh-cut potatoes exhibited a slight and acceptable sweet aroma, which quickly disappeared after heat cooking. Further research revealed furaneol reduced the activity of polyphenol oxidase (PPO), chelated Cu2+, and acted as a mixed-type inhibitor of PPO with competitive inhibition being the dominant. Circular dichroism analysis indicated furaneol decreased α-helix content, increased the β-fold content, and altered the secondary structure of PPO. Fluorescence quenching data showed furaneol can form complexes with PPO, quench the fluorescence produced by PPO and change its tertiary structure. Molecular docking suggested that furaneol could enter the active center region near copper ions and interact with surrounding amino residues through van der Waals force, pi-alkyl interactions and carbon-hydrogen bonds. Furaneol can also cause the brown pigment colorless to a certain extent. Moreover, furaneol addition also improved the antioxidant capacity of enzymatic browning reaction system. Our study first reported the inhibitory effect of furan compounds on enzymatic browning and furaneol has great potential as an anti-browning inhibitor for fresh-cut produce in future. • Our study first reported the inhibitory effect of furaneol on browning. • Furaneol reduced PPO activity by chelating Cu2+ and interacting with residues. • Furaneol acted as a mixed-type inhibitor of PPO. • Furaneol formed a complex with PPO, influencing the structure of PPO. • Furaneol improved the antioxidant capacity of enzymatic browning reaction system. [ABSTRACT FROM AUTHOR]

Minimally processed fruit presents a short shelf‐life because of cellular endogenous metabolism or microbial development. Fruit browning mostly results from phenolic compound oxidation. Banana (Musa acuminata Cavendish) cuts are particularly prone to enzymatic browning, resulting in unattractive color and modifications of aroma. In this study, the effect of two different eco‐sustainable packaging films on minimally processed banana is investigated. The films differ by the substrate, either polyethylene terephthalate (PET) or a fully biodegradable mix of polylactic acid (PLA) and polybuthylene adipate terephtalate (PBAT). They are coated with an amorphous PLA layer containing as antioxidant an active agent deriving from olive processing wastes. Minimally processed banana slices are prepared, packed, and stored at 4°C. Microbiological quality, color, pH, firmness, and polyphenol oxidase activity are evaluated during storage. The PET films show a better efficacy to limit browning, mainly due to the higher oxygen barrier properties compare to the PLA/PBAT. Best results are obtained with PET films with 5% of active phase. [ABSTRACT FROM AUTHOR]

Fresh Lentinus edodes (L. edodes) are prone to browning (including enzymatic and nonenzymatic browning), which affects their quality and leads to economic losses during later processing. This study explored various effective color protection methods (color protection reagent and/or blanching) for inhibiting the browning of L. edodes. First, a single‐factor experiment and a response surface method were used to optimize the concentration of the color retention reagent. The compound color retention reagent (comprising 0.1% phytic acid, 0.8% sodium citrate, and 0.5% d‐sodium erythorbate) had the smallest total color difference (ΔE) value, suggesting that the compound color reagent had a better inhibiting effect than the single agent. Following this, the blanching conditions were studied; the polyphenol oxidase (PPO) activity was the lowest when the blanching temperature was 90°C and blanching time 180 s, indicating that browning is likely to be minimal. Finally, comparing the oxidase activity and total color difference (ΔE) revealed that combining the two color protection methods inhibits browning better than using a single method (color protection reagent or blanching). In addition, the polysaccharide and vitamin C (VC) contents of L. edodes under optimal color protection conditions were determined, which were 0.96 and 2.54 g/100 g fresh weight (FW), respectively. The results demonstrated that this color protection method effectively inhibits browning, reduces the nutritional loss, and improves the quality of L. edodes. [ABSTRACT FROM AUTHOR]

This study aims to disentangle avocado enzymatic browning by identifying and analyzing the PPO coding genes. Two avocado accessions (AVO48 and San Miguel) and the Hass cultivar with contrasting browning kinetics and enzyme activity levels were selected for gene characterization. Upon 90 min of light exposure, Hass and San Miguel showed a greater decrease in luminosity retention (closer to 40% of initial luminosity) compared to AVO48 (85% of luminosity). PPO activity in crude extracts was significantly higher (P < 0.05) in San Miguel (696 U μg-1 protein) than Hass (174 U μg-1 protein) and AVO48 (46–56 U μg-1 protein). San Miguel showed a higher Vmax Km-1 ratio (20.88 min-1), followed by Hass (14.29 min-1) and AVO48 (1.64 min-1), suggesting that San Miguel and Hass have higher substrate affinity. Four PPO coding genes: PamPPO1, PamPPO2, PamPPO3 and PamPPO4 were identified in the Hass genome, all of them containing the main features of plant PPOs, but with specific amino acid combinations in the catalytic pocket of the tyrosinase domain; suggesting that PPO1, PPO2 and PPO4 have monophenolase activity, whereas PPO3, has o-diphenolase activity. The evidence of transcription of PPO3 in fruit of the three genotypes suggests an important role for this gene in avocado pulp browning. PPO2 expression was only found in AVO48. This research provides gene candidates for selective silencing to reduce enzymatic browning. [ABSTRACT FROM AUTHOR]

Litchi, a tropical and subtropical fruit with substantial commercial value, is prone to browning after harvest. Phytosulfokine (PSK), a plant peptide hormone, plays a significant role in postharvest fruit preservation by affecting various biological processes. However, its specific effects on litchi browning have not been fully elucidated. This study demonstrates that PSK application effectively delays litchi pericarp browning, maintains a higher TSS/TA ratio, and reduces electrical conductivity. PSK treatment inhibits the degradation of anthocyanins, flavonoids, and phenolics, while also decreasing the accumulation of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and superoxide anions (O₂⁻). Additionally, PSK enhances the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR), while reducing the activities of ascorbate peroxidase (APX), polyphenol oxidase (PPO), and peroxidase (POD) compared to the control. Transcriptome analysis reveals that PSK upregulates genes involved in plant hormone signaling and biosynthesis of anthocyanins and flavonoids, while downregulating genes associated with glutathione metabolism and autophagy. RT-qPCR confirms that PSK treatment decreases the expression levels of APX , LAC7 , PPO , POD1 , POD5 , POD51 , and PODX , while increasing the expression of GPX4 , contributing to the delayed browning. These findings suggest that PSK mitigates litchi browning by modulating oxidative enzymatic reactions and suppressing the expression of browning-related genes. • PSK application delays senescence and reduces pericarp browning in litchi fruits. • PSK boosts SOD, CAT, and GR activities, but reduces APX, PPO, and POD activities. • PSK enhances hormone signaling and anthocyanin biosynthesis genes expression. • PSK downregulates genes linked to glutathione metabolism and autophagy. • PSK delays litchi browning by regulating antioxidant enzymes and browning genes. [ABSTRACT FROM AUTHOR]

Litchi fruit is extremely vulnerable to postharvest browning due to its perishable physiological characteristics, which seriously restricts the shelf-life and industrial development of products. Trehalose is a natural product with excellent biological activity and safety. In this work, the ability of trehalose to mitigate the browning of 'Feizixiao' litchi fruit stored at 25 °C and its physio-biochemical mechanisms were evaluated. The application of trehalose at 2.5 g L−1 to litchi fruit delayed browning and redness loss. Trehalose treatment alleviated oxidative stress-induced impairment of membrane system, as indicated by reduced generation of O 2 -., H 2 O 2 and malondialdehyde (MDA) and lowered relative electrolyte leakage (REL), which was a result of increased activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). Compared to control fruit, repressed activities of polyphenol oxidase (PPO) and peroxidase (POD) coincident with higher contents of total phenolics, flavonoids, anthocyanins, procyanidin B2 and cyanidin-3-O-glucoside were observed in fruit receiving trehalose, indicating an amelioration of enzymatic browning by trehalose treatment. Furthermore, trehalose treatment stimulated the expression of anthocyanin biosynthetic genes (LcPAL , Lc4CL , LcCHS , LcCHI , LcANS , LcDFR and LcUFGT) and their transcriptional activator genes (LcMYB43435 , LcMYB18362 , LcMYB30086 and LcMYB2539), while suppressing the transcription of microRNAs (miR159 , miR319 , miR828 and miR858) that mediate MYB degradation. Additionally, trehalose treatment increased content of adenosine triphosphate (ATP) and expression of LcPGK and LcCa 2+ -ATPase , while repressing the transcription of miR2118 that can target and negatively regulate LcPGK and LcCa 2+ -ATPase , which facilitated the synthesis and utilization of energy. These findings suggest that trehalose could retard postharvest browning in litchi fruit by enhancing antioxidant capacity, promoting anthocyanin synthesis and maintaining energy homeostasis. • Trehalose (2.5 g L−1) delays browning in litchi fruit during ambient storage. • Trehalose reinforces antioxidant capacity in litchi fruit during storage. • Trehalose inhibits enzymatic browning in litchi fruit during storage. • Trehalose positively regulates anthocyanin synthetic pathway in stored litchi fruit. • Trehalose promotes energy production and utilization in litchi fruit during storage. [ABSTRACT FROM AUTHOR]

Enzymatic browning is a major problem that seriously impacts the quality of fresh-cut potatoes. Our previous study found that glutamic acid (Glu) treatment could repress the discoloration of fresh-cut potatoes, but the molecular mechanism was still unknown. Herein, it was found that the content of total phenolic, H 2 O 2 , O 2 .- and the activities of PPO, POD and PAL were repressed, but the activities of CAT, APX, SOD and GPX were improved by Glu treatment. Moreover, transcriptomic analysis showed that an abundant number of differentially expressed genes (DEGs) were selected from fresh-cut potatoes browning between Glu and control groups. A comprehensive functional enrichment analysis showed that the metabolic pathways of glutathione metabolism, flavonoid biosynthesis, phenylalanine metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction were markedly enriched, which transcriptional levels were markedly altered by Glu treatment. RT-qPCR confirmed the results of RNA-Seq that Glu repressed the transcription of StPPO2 , StPPO3 , StPPO7 , and StERF-BR1-like. More importantly, as a nuclear protein, StERF-BR1-like activated the transcription of StPPO2 by directly binding with its promoter. Overall, these data indicate that Glu could repress the browning of fresh-cut potatoes by regulating the pathways mentioned above, and StERF-BR1-like may involve this process by stimulating the expression of StPPO2. • Glutamic acid (Glu) treatment inhibits the activities of PPO, POD and PAL. • Plant hormone and antioxidant enzyme play an important role in fresh-cut potatoes. • Glu treatment severely affects the transcription level during browning in potatoes. • StERF-BR1-like4 mediates the browning of fresh-cut potatoes by regulating StPPO2. [ABSTRACT FROM AUTHOR]

Manna is the sap extracted in summer from the phloem of the stem and the old branches of Fraxinus sp. trees. Its composition is characterized by a high content of D-mannitol, gallic acid, tyrosol and a great antioxidant activity. The aim of the present work was to compare the effect of a solution enriched with manna or calcium ascorbate, the latter widely used by researchers as an antioxidant agent on the control of browning of apple slices. After harvest, apple fruit were cut, treated with manna (MN), calcium ascorbate (CA) or with distilled water as a control (CTR), and packed in polylactic acid (PLA) packaging. Physical, chemical and sensory analyses were performed after 3, 5, 7 and 10 days of storage at 5±0.5 °C. After one week of storage, manna and calcium ascorbate-based treatment significantly inhibited apple fruit slices browning of cut surface, to the same extent, while no significant differences occurred in terms of weight loss, DPPH, total carotenoids and flavor score. On the whole, manna may inhibit apple slices water loss without affecting fruit flavour and providing the maintenance of their shelf-life. It seems that manna and calcium ascorbate mechanism and effect on browning inhibition are very similar and account for maintaining stored apple slices shelf-life up to 7 days. Therefore, our work lays the foundations for the use of manna as a natural antioxidant compound capable of reducing fresh-cut enzymatic browning • Manna composition is characterized by gallic acid, tyrosol and antioxidant activity. • Manna treatment reduced softening and weight loss. • Manna and calcium ascorbate effect on browning inhibition are very similar. • Manna treatment application didn't affect apple slices flavor. • The increases of phenols can promote browning on the cut surface of apple. [ABSTRACT FROM AUTHOR]

Copyright of Agroindustrial Science is the property of Agroindustrial Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the efficacy of 40‐kHz (200 W) ultrasonication (US) for 2 min combined with glutathione (GSH) at 0.5% w/v (US + GSH) in preventing browning and preserving the physicochemical quality of lotus rhizome slices stored in a 4 ± 1 °C refrigerator. According to the visual appearance of the slices, US + GSH treatment more effectively inhibited the browning of the cut surface than did GSH or US treatment alone. US + GSH and GSH treatments were more effective than US and control treatments in preserving the slices' colour attributes, such as their lightness and whiteness index values, and potentially retarded enzymatic browning reactions and increases in browning index and total colour difference values. Moreover, the application of US and US + GSH treatments noticeably preserved the texture of the slices. None of the treatments affected the total sugar content during storage. The US + GSH treatment markedly enhanced the ferric reducing antioxidant potential of the slices during storage. The slices treated with US, GSH, and US + GSH exhibited slower reductions in 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical scavenging activity than did the controls. In conclusion, US + GSH treatment is a feasible approach for inhibiting browning, maintaining texture, and inducing antioxidant activity in lotus rhizome slices during storage. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Sociedad Química del Perú is the property of Sociedad Quimica del Peru and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• LVEF-Vac treatment slows down browning of white Hypsizygus marmoreus during storage. • Regulation of gene activity to inhibit enzymatic browning. • Reduction of non-enzymatic browning by inhibition of partial amino acid production. A study was conducted to examine the effects of postharvest anti-browning of white Hypsizygus marmoreus and the enzymes related to it, utilizing the Low Voltage Electrostatic Field-Vacuum (LVEF-Vac, 150 V, 100 Hz, 26–36 kPa) treatment technology. The findings indicated that the application of LVEF-Vac treatment significantly extended the storage time of white Hypsizygus marmoreus to 14 d as compared to the control groups. Additionally, it successfully prevented the rise in color difference and browning degree, reduce them by 21.23 % and 36.62 %, respectively, while also inhibiting water loss and migration. Furthermore, it can impede the increase in total amino acid, tyrosine, and lysine content while maintaining a high proline and total phenols content of white Hypsizygus marmoreus during storage. At 9 d of storage, LVEF-vac treated laccase activity was reduced by 32.56 %, tyrosinase activity was reduced by 40.35 %, and gene expression of laccase and tyrosinase was reduced by 93.67 % and 48.77 %, respectively. Therefore, the discoloration of white Hypsizygus marmoreus during storage is slowed down, which improves its quality over time. [ABSTRACT FROM AUTHOR]

In this study, the inhibitors of apricot browning were analyzed by investigating the effects of osmotic dehydration (OD) pretreatment combined with chlorogenic acid (CA) on cell disruption, loss of phenolic substrates, and changes in key enzymes during freeze-thawing. Both OD and OD-CA mitigated the deterioration caused by ice crystal damage during freeze-thawing. OD and OD-CA significantly reduces the BI of apricots by 43.27 and 59.55 compared to CK. The PPO and POD activity in OD-CA apricots are only 61.11% and 42.13% of those in OD. OD-CA could also protect SOD and CAT activity, with their activity in the OD-CA being 1.41 and 1.14 times that of OD group. This indicated that OD-CA treatment protected against the activities of ROS-scavenging enzymes. Compared with OD, OD-CA could better protect the bioactive substance of apricot. The contents of ascorbic acid, total phenols, and total flavonoids in OD-CA were 1.32 times, 1.11 times, and 1.05 times higher than those in OD. OD-CA also effectively protected chlorogenic acid, neochlorogenic acid, cryptochlorogenic acid, catechins, and rutin. In summary, OD-CA primarily reduced the browning by protecting the integrity of cell structures, minimizing the potential for exposure to air, enzymes, and phenolic substrates, and inhibiting browning enzymes activity. • Both OD-CA and OD effectively inhibited freeze-thaw browning of apricots. • OD changed the freezing characteristics of apricots and reduced ice crystal damage. • OD inhibited apricot browning by reducing contact between polyphenols and enzymes. • CA treatment reduced free radical production in frozen and thawed apricots. [ABSTRACT FROM AUTHOR]

Enzymatic browning is a primary factor affecting the quality of fresh-cut potatoes. Our previous research demonstrated that warming the tubers after cold storage can alleviate the enzymatic browning of fresh-cut potatoes. In this research, we explored if some new endogenous compounds play roles in browning inhibitory effects. Utilizing a non-targeted metabolomics approach on tubers subjected to pre-cutting different temperature treatments, thirteen differential metabolites in potatoes were revealed, and five compounds with anti-browning effects were screened out. Among these five compounds, chenodeoxycholic acid (CDCA) exhibited the best inhibitory effect on browning and has not been reported in plants till now. The changes in CDCA content in tubers of pre-cutting different temperature treatments were further confirmed by LC-MS/MS. Subsequent experiments showed that the anti-browning effect of pre-cutting CDCA treatment was much better than post-cutting. Pre-cutting CDCA treatment only at a low concentration of 5 mg L−1 for a 10 min soaking and then standing for 6 h extended the shelf life of fresh potato slices to 5 d from less than 1 d of control. Not a big difference in polyphenol oxidase (PPO) activity and tyrosine contents were caused by pre-cutting CDCA treatment compared with control. However, pre-cutting CDCA treatment caused a notable reduction in the contents of malondialdehyde (MDA), superoxide anion (O 2 -), H 2 O 2 , and lipoxygenase (LOX) activity, and elevated the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX). Meanwhile, CDCA suppressed phenylalanine ammonia-lyase (PAL) activity and reduced the contents of both individual and total phenolic compounds. These results suggest that CDCA, an endogenous compound in potato tuber, can improve the anti-browning ability of fresh-cut potatoes mainly by inducing the enhancement of antioxidant capacity. • Five compounds with anti-browning effects were screened using non-targeted metabolomics. • Chenodeoxycholic acid (CDCA) was an endogenous anti-browning agent in potatoes. • The anti-browning effect of pre-cutting CDCA treatment was better than that of post-cutting. • Pre-cutting CDCA treatment induced the enhancement of antioxidant capacity. • Pre-cutting CDCA treatment improved the anti-browning ability of fresh-cut potatoes. [ABSTRACT FROM AUTHOR]

China is one of the main producers in the worldwide raisin market. Most China's raisins are produced in Xinjiang where the Thompson seedless grape (Vitis vinifera L.cv.Thompson seedless) is the main variety of green raisin. However, the browning of Thompson seedless grape during drying has been well-acknowledged as the primary factor affecting the development of the raisin industry. Data independent acquisition (DIA)-based protein profiling was performed on fresh and shade-dried Thompson seedless grapes. As a result, 5431 proteins were identified, among which the amounts of 739 proteins in fresh grape were found to be significantly different with those in dried grape. The functional annotation based on the Blast2GO showed that the 'organic substance metabolic process', 'regulation of molecular function', 'enzyme regulator activity', and 'isomerase activity' related proteins became very active during browning. Further analyses revealed that the browning-related proteins, which with significant different amounts in fresh and in dried grapes, are primarily involved in the phenylpropanoid biosynthesis, tyrosine metabolism, phenylalanine metabolism, oxidative phosphorylation metabolism, plutathione metabolism, peroxisome pathway, and fatty acid degradation. And five random differential proteins were verified with parallel reaction monitoring (PRM). The PRM results were in agreement with the DIA data. The main browning-related proteins of Thompson seedless grape were identified in this study. Their properties were tested, and their roles in the browning mechanism were indicated. This will lay base to a better understanding on the enzymatic browning of Thompson seedless grape, and it will also provide guidance for controlling the quality of Thompson seedless grapes in industry. [ABSTRACT FROM AUTHOR]

Aloe vera (ALV) with its unique nutritional profile is being used for food, health, and nutraceutical industries globally. Due to its organic nature, ALV gel coating has created lot of interest for exploring its potential in extending the shelf and storage life of fresh produce. ALV gel coating plays imperative role in delaying fruit ripening by lowering ethylene biosynthesis, respiration rate, and internal metabolic activities associated with fruit softening, color development, enzymatic browning, and decay. ALV gel coating reduces the microbial spoilage due to its antifungal properties and maintains visual appearance, firmness, sugar: acid ratio, total antioxidants, and phenolic contents with conserved eating quality. ALV coated fruits and vegetables showed reduced weight loss, superoxide ion (O2-), hydrogen peroxide (H2O2), ion leakage, and soluble solids content and exhibited higher acidity, anthocyanins, ascorbic acid, catalase (CAT), superoxide dismutase (SOD), and ascorbate peroxidase (APX) activities. It also delayed the enzymatic browning by inducing peroxidase (POD) activity during storage. Recent local studies also revealed that ALV gel coating markedly conserved higher consuming quality and extended storage period (>1.34-fold) of different fruits and vegetables. Overall, Aloe vera gel coating alone or in combination with other organic compounds has shown great potential as a food-safe and eco-friendly coating for maintaining the quality of fruits and vegetables over extended period and reducing postharvest losses in the supply chain. Practical applications: ALV gel is a plant-based natural coating of eco-friendly nature. The present review summarizes the updated information of ALV gel coating application, methods of extraction, combinations with other postharvest coatings, and its impact on quality of various fruits and vegetables. It also provides future insights for the development of commercially applicable ALV gel coating protocols through simulation studies. So, being a natural coating, ALV gel has tremendous potential to be used in fruit and vegetable industries around the globe. [ABSTRACT FROM AUTHOR]

The purification of the polyphenol oxidase (PPO) enzyme from Kirmizi Kismis grape (Vitis vinifera L.) was performed 61.23 times using affinity chromatography. The molecular weight of the enzyme was found to be about 38.1 kDa by SDS‐PAGE as a single band. The optimum pH and temperature values were revealed to be 5.0 and 30°C, respectively, in the presence of 4‐methyl catechol substrate. The thermal stability of PPO was examined and it was observed to maintain its activity at 20°C for 1 hr. Km and Vmax values were determined to be 4.8 mM and 2000,0 EU/ml for 4‐methyl catechol as a substrate. IC50 and Ki values and inhibition types were found for various browning agents and ascorbic acid had the strongest inhibitory impact on PPO. The inhibitory impact of Na+, K+, Mg2+, Cu2+, and Al3+ metal ions on the enzyme activity at final concentrations of 1 mM and 10 mM was examined. Practical applications: Grapes grown and processed take a significant place in our life. The grape has antioxidant, anticarcinogenic, antidiabetic and protective properties against bacteria and viruses. Furthermore, it takes an important position in the country's economy and social life due to providing raw materials to the food industry and having high export potential. Polyphenol oxidase, which is the leading actor of enzymatic browning reactions causing serious economic losses every year, was purified and characterized from Kirmizi Kismis grape (Vitis vinifera L.). This ancient grape variety has industrial processing and export potential due to its long storage life and resistance to oxidation. Therefore, the purification and biochemical characterization of polyphenol oxidase from Kirmizi Kismis grape are of great importance. [ABSTRACT FROM AUTHOR]

This research is to rate the inhibition of Polyphenol Oxidase enzyme in a paste made of avocado (Persea Americana Mill) variety Hass through an onion peel (Allium Cepa) from two sorts of bulbs, white one and red one; exposed to two thermic treatments over 100°C and 115°C aiming to inhibit the effect of Polyphenol Oxidase which convert Phenols into Quinones causing the enzymatic browning. So that it implied to perform diversity of treatments, employing an inhibitor agent on different concentrations and periods of time in order to determine the ideal applications on determined times which required measuring the absorbance in four treatments, 1:0, 1.1, 1.2 and 2.1 respectively corresponding to the enzyme and the inhibitor agent, as a result of the enzymatic activity test a complete inhibition was reached for a concentration of 1:2 for the white bulb onion case in temperature of 100°C related to enzyme substratum; in red bulb onion case the inhibition varied for each treatment. [ABSTRACT FROM AUTHOR]

• Acetic acid is a promising food-derived browning inhibitor. • Acetic acid strongly delays the discoloration of fresh-cut cassava. • Acetic acid can inhibit enzymatic browning by inhibiting PPO, PAL and POD. • Acetic acid reduces the accumulation of phenolic, flavonoid, ROS and MDA. Cassava is one of the important commercial crops in tropical and subtropical regions. However, cassava browning is an important factor restricting its postharvest storage, shelf life and quality. Therefore, suitable approaches are needed to control fresh-cut cassava browning. Acetic acid alleviates the effects of different abiotic stresses and prolongs the shelf life of food. The study aimed to study the effects of exogenous acetic acid on postharvest browning in fresh-cut cassava. The results showed that acetic acid treatment strongly delayed the discoloration during storage through reducing the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), peroxidase (POD), and inhibiting the generation of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as accelerating loss of total phenolic and flavonoid. Notably, acetic acid treatment markedly promoted the accumulation of acetic acid, delayed loss of total starch and had slight impact on jasmonic acid (JA). In addition, JA treatment also delayed discoloration during cassava storage. These findings suggested that the delay of cassava browning via acetic acid treatment could be attributed to maintenance of redox homeostasis by modulating repair of oxidatively damaged proteins, providing a new way to prevent the browning of fresh-cut cassava and elucidates the anti-browning mechanism of acetic acid treatment. [ABSTRACT FROM AUTHOR]

• Browning of young 'Moriya' persimmon involves biological membrane degradation. • PPO, POD and polyphenols eluted from the damaged membrane and react in the cytoplasm. • Increased expressions of DkPLDs and DkLOX3 affected membrane degradation. • Ascorbic acid's antioxidant activity may curb PPO and POD's phenolic oxidation. Determining the mechanism of fruit tissue browning is important to prevent fruit quality degradation and reduce fruit loss at the postharvest stage in persimmons. We aimed to provide a fundamental understanding of the mechanism of browning of mature persimmon fruit and contribute to develop a method for its prevention over the course of the marketing supply chain by analyzing the browning of young immature persimmon fruit. Tissue browning was first observed seven days after harvest (DAH), and spontaneous ethylene production was initiated at five DAH. The activities of the browning enzymes polyphenol oxidase (PPO) and peroxidase (POD) were sufficiently high to induce fruit tissue browning. As these enzymes are normally sequestered by biological membranes in cells, we hypothesized that biological membrane degradation occurs prior to browning. Electrolyte leakage and the increase in malondialdehyde content occurred during storage. An increase in malondialdehyde content provided evidence of progressive membrane degradation. The increased expression of phospholipase relative DkPLD alpha1, DkPLD beta/gamma1 , and lipoxygenase relative DkLOX3 genes, probably induced by ethylene, indicated their significant roles in membrane degradation. The ascorbic acid may play a role in inhibiting the oxidation of phenolic substrates by PPO and POD owing to its antioxidant activity. The results of our study suggest that the hydrolysis of phospholipids by DkPLD alpha1 and DkPLD beta/gamma1 and peroxidation by DkLOX3 promote biological membrane degradation in both persimmon skin and flesh. Additionally, we hypothesized that the decrease in L-ascorbic acid content could induce browning, as a result of PPO and POD leaked from the biological membrane could react with phenolic substrates. [ABSTRACT FROM AUTHOR]

• Exogenous H 2 O 2 can enhance Prx/Trx system enzyme activities in fresh-cut guava. • Exogenous H 2 O 2 can maintain NADPH redox balances in fresh-cut guava. • H 2 O 2 affects Prx/Trx system to reduce oxidative damage and browning. Abiotic stresses in plants are commonly caused by antioxidant system imbalance in their tissues. A peroxiredoxin/thioredoxin (Prx/Trx) system is a ubiquitous antioxidant system involved in sensing and detoxifying hydrogen peroxide (H 2 O 2) and other reactive oxygen species (ROS). This study investigated exogenous H 2 O 2 potential in reducing browning and its interaction with the Prx/Trx system in fresh-cut guava fruit during storage at 25 °C. Fresh-cut guava samples were immersed in 0 (control) and 250 mM H 2 O 2 for 10 min, placed on a foam tray, packed inside a polyethylene bag and kept at 25 ± 1 °C for 48 h. The H 2 O 2 treatment reduced browning and maintained fresh-cut guava fruit quality during storage. The H 2 O 2 treatment reduced oxidative membrane damage and an accumulation of ROS, but activated the Prx/Trx system by stimulating the activities of peroxiredoxin and thioredoxin reductase, and NADPH-generating dehydrogenases including glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase as well as an increase in NADP redox state. The altered redox state and the activation of the Prx/Trx system by H 2 O 2 was correlated with delayed browning of fresh-cut guava. Thus, the Prx/Trx system is involved in browning development, and H 2 O 2 treatment could delay browning in fresh-cut guava by reducing oxidative membrane damage via stimulating the Prx/Trx system. [ABSTRACT FROM AUTHOR]

Proline is one of the amino acids that compose proteins and has various roles under non-stress and stress conditions. In this study, we investigated the effect of proline on the growth and browning of two plants, tobacco and rice, by exogenous application and endogenous increase of proline. Exogenous proline had a different effect on the growth and browning between tobacco and rice: proline affected negatively the growth of tobacco seedlings and favorably that of rice seedlings. In addition, proline prevented browning only in rice cultured cells, consistent with the increase of proline contents, but not in tobacco BY-2 cells. These results might be due to the difference of exogenous proline uptake activity in these cells. From the Lineweaver-Burk plots, proline inhibited polyphenol oxidase activity in vitro, which is a major factor of enzymatic browning in plants, by affecting the enzyme-substrate complex. Proline could suppress the browning of the plant callus by inhibition of PPO activity. Image 1 • Exogenous proline had different effects on the growth of tobacco and rice seedlings. • Endogenous and exogenous proline accumulation suppressed the browning of rice calli. • Proline inhibited polyphenol oxidase activity in vitro. [ABSTRACT FROM AUTHOR]

Highlights • The effect of UV-C treatment on the quality of lotus root was investigated. • The inhibiting browning mechanism of UV-C was studied. • The optimum condition of UV-C radiation was treated for 5 min. • Low PPO, POD, PAL activities and less damage degree of the cell inhibited browning. Abstract The effect of shortwave ultraviolet (UV-C) radiation on the quality, especially browning of fresh-cut lotus (Nelumbo nucifera Gaertn.) root in relation to enzymes and phenolic metabolism was investigated. Fresh-cut lotus roots were exposed to UV-C lamp (75 W) at a distance of 30 cm above the produce tray for 1, 5, 10, 20, and 40 min, and then stored for 8 days at 4 °C. Results showed that UV-C treatments for 5 and 10 min exhibited significantly low browning degree, soluble quinone content and inactivation of polyphenol oxidase, peroxidase, and phenylalanine ammonia lyase activities, while other qualities including soluble solids content and hardness had no difference with other treatments. Prolonging treatment time had less effect on inhibiting the browning since a long time of UV-C radiation increased cell damage. In summary, UV-C treatment has the potential to maintain quality of fresh-cut lotus root. [ABSTRACT FROM AUTHOR]

Highlights • Quantify the browning of tender jackfruit slices using image analysis technique. • Comparing results from sensory test, enzyme activity and colorimeter. • Variation in rate of browning of fresh cut tender jackfruit slices with time. • Prevention of browning by using different packaging techniques. Abstract Changes in physicochemical properties of fresh cut tender jackfruit during storage is depend on its colour. Colorimeter measurements are best for the samples with homogeneous colour. However, for samples with non-homogenous colors or large sizes (like fruits and vegetables), the colorimeters are inappropriate and inaccurate. The aim for this study is to quantify the amount of browning in fresh cut tender jackfruit slices by using image analysis technique and justify the results by comparing them with existing techniques like sensory examination, enzyme activity, and colorimeter. It can be concluded from the results that browning in fresh cut tender jackfruit slices increase rapidly in control and normally packed samples. Correlation coefficient as high as 0.963, represent that image analysis system is an accurate and highly consistent method to quantify the colour of fruits and vegetables. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The research was conducted to investigate the quality changes of basic physicochemical indicators, functional components and appearance, such as, pH, total color difference, Browning Index, polyphenols, flavonoids, anthocyanins, VC, and 5-hydroxymethylfurfural content and so on of Dendrobium officinale flower juice (DOFJ) under the dark storage conditions of 4, 25 and 37 °C and the natural light irradiation storage conditions of 25 °C for 8 weeks. Correlation and path analyses were used to analyze the causes of color degradation of DOFJ. Although measures had been taken during the preparation process to inhibit enzymatic browning by deactivating the activity of polyphenol oxidase (PPO), DOFJ was still unstable under four storage conditions, especially for color degradation. With the increase of temperature and time, the basic physicochemical indexes did not change significantly, but the content of functional components gradually decreased, and the appearance gradually deteriorated. The path analysis indicated that anthocyanins degradation was the key factor of color degradation of DOFJ, and low temperature and light protection could delay the degradation of anthocyanins. The main cause of color degradation of DOFJ during storage was identified, which provided a basis for further inhibiting color degradation of flower juice. • Causes of color degradation of DOFJ were determined by path analysis. • DOFJ was unstable during storage, the stability decreased as temperature increased. • Low temperature and light protection could delay the degradation of anthocyanins. • Anthocyanins degradation was major factor due to the color degradation of DOFJ. [ABSTRACT FROM AUTHOR]

Enzymatic browning is a major issue that needs to be solved in the food industry. Although swertiajaponin is a flavonoid rich in the whole herb of Swertia japonica that has been clinically used, its biological functions and applicat​ion in the foods have not been fully elucidated. Here, we showed that swertiajaponin efficiently blocked enzymatic browning in potatoes possibly by direct binding to and inactivating polyphenol oxidase. Furthermore, swertiajaponin showed potent antioxidant activity proven by markedly suppressed reactive oxygen species. Swertiajaponin significantly increased antioxidant properties of potato extract when it is added since it additively elevated total flavonoid content. Considering numerous beneficial effects of antioxidants, swertiajaponin may be used as a functional food additive to suppress enzymatic browning and elevate the antioxidant capacity of foods including beverages and soups by fortification of flavonoids. [ABSTRACT FROM AUTHOR]

During cold-exposure ‘beige’ adipocytes with increased mitochondrial content are activated in white adipose tissue (WAT). These cells, similarly to brown adipose tissue (BAT), dissipate stored chemical energy in the form of heat with the help of uncoupling protein 1 (UCP1). We investigated the effect of tissue transglutaminase (TG2) ablation on the function of ATs in mice. Although TG2 +/+ and TG2 −/− mice had the same amount of WAT and BAT, we found that TG2 +/+ animals could tolerate acute cold exposure for 4 h, whereas TG2 −/− mice only for 3 h. Both TG2 −/− and TG2 +/+ animals used up half of the triacylglycerol content of subcutaneous WAT (SCAT) after 3 h treatment; however, TG2 −/− mice still possessed markedly whiter and higher amount of gonadal WAT (GONAT) as reflected in the larger size of adipocytes and lower free fatty acid levels in serum. Furthermore, lower expression of ‘beige’ marker genes such as UCP1, TBX1 and TNFRFS9 was observed after cold exposure in GONAT of TG2 −/− mice, paralleled with a lower level of UCP1 protein and a decreased mitochondrial content. The detected changes in gene expression of Resistin and Adiponectin did not provoke glucose intolerance in the investigated TG2 −/− mice, and TG2 deletion did not influence adrenaline, noradrenaline, glucagon and insulin production. Our data suggest that TG2 has a tissue-specific role in GONAT function and browning, which becomes apparent under acute cold exposure. [ABSTRACT FROM AUTHOR]

Core browning is a major issue of pear fruits. The primary factor leading to development of core browning is high levels of CO 2 in storage. Hypobaric storage is a new postharvest technique to extend the shelf life of fruits and can reduce CO 2 partial pressure. In this study, the effect of hypobaric storage on core browning of Yali pear fruits ( Pyrus bretschneideri Rehd.) was evaluated. Results showed that fruits after 0.025 MPa hypobaric treatment had 37.3% lower rate of core browning development and higher acidity and soluble solid content than control fruits. In addition, 0.025 MPa hypobaric treatment increased activities of cytochrome oxidase (CCO) and peroxidase (POD), and 2,2-diphenylpicrylhydrazyl (DPPH) radicals and superoxide anion scavenging capabilities. In comparison with the control, hypobaric treated fruits had lower activity of polyphenol oxidase (PPO) and higher level of total polyphenols. Hypobaric treatment also reduced an increase of succinate dehydrogenase (SDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) activities. Results indicated that hypobaric treatment could control core browning of pear fruits by regulating reactive oxygen species (ROS) generation and elimination enzymes to maintain cell membrane integrity and reduce enzymatic browning. [ABSTRACT FROM AUTHOR]

The disinfection efficacy of acidic electrolyzed water including slightly acidic electrolyzed water (SAEW) and strongly acidic electrolyzed water (AEW) on the fresh-cut lotus roots and their effects on the appearance quality of fresh-cut lotus root were evaluated in the present paper. The results showed that SAEW treatment could reduce the natural microbial flora populations as well as the inoculated populations of fresh-cut lotus roots significantly. Also, our results obtained from the present study suggested that SAEW treatment could maintain the appearance quality and market values more effectively than acidic electrolyzed water (AEW) treatment. Considering that SAEW is environmentally friendly and has dual efficacy of disinfection and browning-prevention, it may be a better choice in the processing of fresh-cut lotus roots. The results implied that SAEW could inhibit the polyphenol oxidase (PPO) activity, thus keep the overall visual quality. However, how SAEW treatments affect PPO activity of the fresh-cut lotus roots is still unknown and further research is needed. Practical applications How to prevent the quality deterioration of fresh-cut lotus root, which limited its safety and processing, had become a serious problem. In the past, the strong disinfection efficacy of acidic electrolyzed water (AEW) and its application in food industry including the disinfection of fruits and vegetables were widely reported. Due to its neutral pH and lower available chlorine concentration (10-30 mg/L), slightly acidic electrolyzed water (SAEW) showed a promising prospect in the agriculture and food industry. In the present study, the disinfection efficacy of SAEW on the fresh-cut lotus roots was investigated. Moreover, the effect of SAEW treatment on the appearance quality of fresh-cut lotus root was evaluated. This study confirmed that SAEW treatment might have a high potential for practical use in the processing fresh-cut lotus roots processing. [ABSTRACT FROM AUTHOR]

Fresh-cut lotus root slices were treated with 80 nM 24-epibrassinolide (EBR) and then stored at 4 °C for 8 days to investigate the effects on cut surface browning. The results showed that EBR treatment reduced cut surface browning in lotus root slices and alleviated membrane lipid peroxidation as reflected by low malondialdehyde content and lipoxygenase activity. EBR treatment inhibited the activity of phenylalanine ammonia lyase and polyphenol oxidase, and subsequently decreased phenolics accumulation and soluble quniones formation. The treatment also stimulated the activity of peroxidase, catalase and ascorbate peroxidase and delayed the loss of ascorbic acid, which would help prevent membrane lipid peroxidation, as a consequence, reducing decompartmentation of enzymes and substrates causing enzymatic browning. These results indicate that EBR treatment is a promising attempt to control browning at cut surface of fresh-cut lotus root slices. [ABSTRACT FROM AUTHOR]

Polyphenol oxidase (PPO), peroxidase (POD) activities, brown spot diseases, and the browning incidence of rambutans play an important role after harvest. As an anti-browning and antifungal agent containing bioactive compounds, potent cardamom oil vapour was investigated at 5 and 10 μL/L inhibitors for 28 days to delay browning, reduce disease, and preserve the quality of rambutans. PPO and POD enzymes, disease incidence, colour attributes, total phenols concentrations and antioxidant were evaluated. Delayed browning with decreased PPO and POD activities, a high L*, a low chroma, a low BI value and few disease-related browning incidents were found in rambutans treated with 5 μL/L cardamom oil compared to the control group. The treated rambutans exhibited an enhanced number of total phenolic compounds and antioxidant potential and more free radical scavenging activity to prevent browning and maintain the rambutans' physicochemical qualities for 21 days of storage, compared to the control group, which only lasted seven days without browning. The treated rambutans exhibited strong ferrous chelating activity against ABTS and DPPH radical scavenging activities. This finding showed that cardamom oil vapour could prevent browning, reduce disease, and maintain the physicochemical and microbiological quality of rambutans, which could apply to the real market shipping rambutans. • Cardamom oil at 5 μL/L effectively delayed the surface browning of rambutans. • Cardamom oil vapour inhibited surface browning of rambutans for 21 days. • Cardamom oil prevented weight loss and maintained anthocyanin content in rambutans. • Cardamom oil exhibited the highest inhibitory effect on polyphenol oxidase and peroxidase activities in rambutans. • Smaller pores of treated rambutans played an important role to delay weight loss. [ABSTRACT FROM AUTHOR]

Enzymatic browning during fresh cutting and storage affects the quality and commodity value of fresh-cut potatoes. The study investigated the effects of glutamic acid (Glu) on browning of fresh-cut potatoes. The results showed that Glu treatments significantly reduced the browning of potato pulp and shreds. Treated with the optimum concentration of 15 g/L Glu for 4 min prolonged the shelf-life of fresh-cut shredded potatoes to 5 d at 2–4 °C. Further research revealed that Glu treatment could inhibit the content of the total phenols, regulate the content of 16 free amino acids and repress the activity of polyphenol oxidase (PPO) via lowering pH value and chelating Cu2+. Molecular docking indicates that Glu stable bound to the active site of PPO. These results indicates that Glu treatment can inhibit the browning of fresh-cut potatoes by inhibiting PPO activity and the total phenolic content and regulating amino acid metabolism. • Glu treatment inhibits the browning of fresh-cut potatoes. • Glu treatment inhibits the total phenols and regulates the content of 16 free amino acids. • Glu treatment represses the activity of PPO via lowering pH value and chelating Cu2+. • Glu could stable bind to the active site of PPO. [ABSTRACT FROM AUTHOR]

• Ethanol maintained storage quality and delayed enzymatic browning. • Ethanol suppressed phenolic metabolism and enhanced antioxidant ability. • Ethanol changed microbial diversity. This study evaluated the changes in phenolic and reactive oxygen species metabolism, and microbial diversity in fresh-cut lotus roots following ethanol treatment to elucidate the potential mechanisms of ethanol in controlling microbial growth and browning. Activity suppression and gene expression downregulation of phenylalanine ammonia-lyase, polyphenol oxidase, and peroxidase took place with ethanol treatment, resulting in the decreased accumulation of total phenols and soluble quinones. The total phenol and soluble quinone contents of ethanol-treated slices were 12.63% and 30.22% lower than those in the control group, respectively, after 12 d of storage. Ethanol treatment changed the level of eleven individual phenols, two of which were associated with antioxidant ability. Besides, the ethanol-treated slices exhibited the reduced production of reactive oxygen species, increased activities of superoxide dismutase and catalase, improved ascorbic acid contents and 1,1-Diphenyl-2-picrylhydrazyl scavenging rate, and the upregulated transcriptional levels of NnGR and NnGST. Moreover, the integrated transcriptomic and metabolomic analyses show the biosynthesis of syringin (an antioxidant in various medicinal plants) might be stimulated by ethanol treatment. Ethanol treatment inhibited the abundance of Pantoea, Pseudomonas, Tolumonas and Stenotrophomonas. These findings suggested ethanol treatment is a simple and potential technology for preserving the quality and antioxidant ability of fresh-cut products. [ABSTRACT FROM AUTHOR]

• The enzymatic browning of catechin is the same as that of non-enzymatic browning. • 1 mM AA had the most effective protective effect on catechin. • The effect of AA on the stability of catechin is time-dependent and dose-dependent. • The antioxidant effect of AA and the addition reaction of DHAA are two key factors affecting the stability of catechin. A series of incubation systems of (+) - catechin (Cat), ascorbic acid (AA) and polyphenol oxidase (PPO) of lotus rhizome at 40 °C were performed to investigate the effect and oxidation pathway of AA on the stability of Cat. The results showed that after the enzymatic or non-enzymatic oxidation of Cat, the products of the two reactions were the same, namely epicatechin, catechin dimer and dehydrogenated catechin dimer. After adding AA, the protective effect of AA on catechin increased first and then decreased with the increase of AA concentration. 0.1 mmolL(exp)-1 AA can inhibit PPO activity in a short time. Within 24 h, 1 mmolL(exp)-1 AA can keep Cat content at 87.88 %. At the concentration of 10 mmolL(exp)-1 AA, excessive AA is oxidized to form a large amount of dehydroascorbic acid (DHAA), which forms an adduct with Cat, promoting the consumption of Cat. The effect of AA on the stability of Cat is time-dependent and dose-dependent. [ABSTRACT FROM AUTHOR]

This study was focused on a comparison between the first order model and the Weibull model regarding their suitability to fit the enzymatic browning kinetic data in samples of mushrooms, pears, apples, avocados, and bananas (based on the use of the L* luminosity, the ΔE*, and the BI as the browning indexes). In order to obtain statistically robust results, at least 900 points by curve kinetic were used to describe the enzymatic browning. A mean square error was used to measure the suitability of each model. In this study, 60 slices from each sample were analyzed in a computer vision system to calculate L* values. In the results, it was demonstrated that the Weibull model appears to be the best model for mushrooms, pears, apples, avocados, and bananas. According to that expected for a First order kinetic, the β values should be equal to one in the Weibull model. In this study, the β values observed were always less than one. Therefore, it is not possible to assert that the enzymatic browning always follows an empirical First order kinetic. According to the results of this investigation, it is recommended to use the Weibull model first to insure that enzymatic browning kinetic is of the first order. [ABSTRACT FROM AUTHOR]

In order to achieve faster drying along with high product quality, microwave freeze-drying (MFD) was applied to dry button mushrooms. Although MFD can lead to similar product quality compared with freeze-drying (FD), the color deterioration of MFD mushroom is higher than FD ones. Therefore, two drying methods were used to investigate the browning behaviors of button mushrooms during MFD in terms of parameters including polyphenol oxidase activity, total phenolic content, moisture content, reducing sugar content, and vitamin C content. It was found that both whiteness and browning degree can be used to describe the browning kinetics of button mushrooms during the MFD process. Both nonenzymatic browning and enzymatic browning took place during MFD of button mushrooms, but the effect of enzymatic browning was more significant, which should be controlled during MFD. In order to avoid enzymatic browning during MFD of button mushrooms, a relatively low microwave power at initial stage of MFD should be adopted. Meanwhile, a low microwave power also should be used at the end stage of MFD so as to reduce nonenzymatic browning. [ABSTRACT FROM AUTHOR]